Flexible vacuum bags are used in various manufacturing and industrial processes, such as the fabrication of composite structures and bonding of parts. For example, in the aerospace industry, without limitation, vacuum bags may be used to bond heat shield tiles to a metal backing. Vacuum bags may also used in vacuum bag molding, wherein a flexible bag formed from a polymer sheet such as Nylon® is placed over a part pre-form and sealed along a mold flange. A vacuum drawn in the bag eliminates entrapped air and excess resin, resulting in compaction of the pre-form. Similarly, vacuum assisted resin transfer molding (VARTM) may employ a vacuum bag to cover a pre-form or dry fabric on one-sided tooling. Air is evacuated and liquid resin from an external reservoir is drawn into the bag which is infused into the pre-form. Any leaks in the vacuum bag may allow air to enter and form bubbles in the resin matrix, resulting in an unacceptable amount of porosity in the matrix. Leaks in the vacuum bag may be relatively small and therefore difficult to observe by an operator. While various gas leak detection techniques are known, they are not always reliable and may not detect leaks quickly enough to be useful in repairing leaks while molding processes are underway.
Accordingly, there is a need for a leak detection system that allows instant detection of the location of leaks in the vacuum bag, without the use of complicated, external leak detection equipment or the need for highly experienced operating personnel. The disclosed embodiments are intended to satisfy this need.